The present invention relates to a fabrication method of a semiconductor device, particularly to a technology effective when applied to a fabrication technology of a semiconductor device capable of equalizing the thickness distribution of a film formed over a semiconductor wafer.
In Japanese Unexamined Patent Publication No. 2004-335923, described is an etching method in which wet etching is carried out by grasping in advance the thickness profile of a film which has been formed on a wafer and is to be processed and discharging an etchant to a thick portion of the film. In this method, simultaneously with the discharge of the etchant, discharge of a dilute solution of the etchant to a thin portion of the film is performed.
In Japanese Unexamined Patent Publication No. 2002-134466, described is a technology of grasping in advance the thickness profile of a film which has been formed over a wafer and is to be processed and discharging an etchant only to a thick portion of the film while moving an etchant nozzle from the peripheral side to the central side of the wafer.
In Japanese Unexamined Patent Publication No. 2005-311012, described is a wet etching apparatus for jetting an etchant while reciprocating a nozzle in a radial direction of a substrate which turns horizontally at a predetermined rotation speed and thereby etching the substrate. This apparatus is equipped with a nozzle speed control means capable of adjusting the moving speed of the nozzle lower on the peripheral side of the substrate than that on the central side thereof.
In Japanese Unexamined Patent Publication No. 2000-212773, described is an apparatus for detecting the completion point of wet etching from a change of wavelength distribution spectrum to be output from a light detection element. In this apparatus, by giving trigger signals which are read integer times from a predetermined region of the light detection element synchronous with the rotation of a turntable integer times to a motor drive circuit and light detection element drive circuit, fluctuations of data to be finally obtained from the light detection element, which fluctuations are attributable to the flickering of the rotation of the turntable, are suppressed and a completion point of the wet etching is detected precisely.